 I think I'm going to change my color again, because at this point, the cladogram becomes all vertebrates. And what is the character that defines vertebrae? I mean vertebrates. Yeah, a spinal cord. So vertebrates have vertebrae. They have this vertebral column. And our first most basal group of vertebrates are lampreys. And they look like eels, but I'm going to show you a picture of them. Those guys are crazy cool. They're a parasitic fish-ish thing. That's not a fish, because it's a lamprey. And it actually attaches itself to a fish and sucks its blood. And you can see that it has this mouth. That isn't a jaw, right? It's like a sucker thing, but it has these teeth things that basically dig a hole in a fish. And if you catch a fish and you see these raw spots, you'll know that there was actually a lamprey attached to that little guy. So they're really interesting, but there's a character that everybody else beyond this point has that they do not have, and that is the jaw. So you notice that, no, they don't have jaws, do they? Nope. So everybody beyond this point has jaws. Now think about who are you going to include in jaw land? What kind of critters have jaws? They're fish. And I say fish, and I'm telling you that what is a fish? That is a group that doesn't tell us a whole lot. There's a lot of different kinds of fish out there, and so I'm grouping them all together. You know what I'm talking about. The fish do not have the next characteristic, which is four limbs. We had a little bit of a conversation. Oh, I'm not going to say that because that will date this video. So fish had fins, and most fish do not have bones in their fins, right? Like they're just like, if you flap a fish's flapper fins, like they're just flappy. It's not bony, it's not a bony structure. There is a group of fish, they're called lobe finned fish, and they do have sort of these bony structures that are kind of jutting out into the finned structure, and that's the precursor for these four limbs. The critters that the most basal group that has four limbs are the amphibians. The amphibians are frogs, salamanders, frogs and salamanders. I feel like there's some more of those things. Why am I not thinking of them? The next group has a thing called the amniotic egg, and what this means is that everybody beyond this point has an amniotic egg. Have we talked about mammals yet? If the answer is no, just in case you just got here. What does that tell you? Mammals have an amniotic egg, do you lay an egg? I didn't lay an egg. However, I have eggs, and when my eggs got fertilized twice, those eggs posted up in my uterus, and I had an amniotic sac, the amniotic fluid, and some little membranes that actually... I basically took my amniotic egg, which is what birds and reptiles have, and I put it inside me. That's what mammals did. And the advantage of an amniotic egg, like how awesome is this? You don't have to lay your egg and then stand around and protect it. You can actually just, it's like posted up inside you, and you can take it wherever you need to go, and it makes you feel massive and awesome. So, yes, mammals do have an amniotic egg. Oops, I want to undo that, because this next one, these guys have an amniotic egg, but I'm going to have to do two branches, because one of my branches is the... I'm going to have to write it all down, non-avian reptile, which means everybody here is a reptile, uh-huh, and the other one is birds. And I know we talked about this briefly, that somewhere, birds are the only living dinosaurs left. So, birds are actually reptiles. They're avian reptiles, and dinosaurs were reptiles that were closely related to birds. They are birds, reptiles, mammals, whatever. Mammals are not birds or dinosaurs. Did you understand anything I just said? Because I don't know if I did. All right, last thing. Throw some mammaries on that clown. Mammary glands. And if you throw some mammaries on there, you've got yourselves a mammal. And I think I have to tell you some mammal stories, because, dude, man, all these critters are so cool. The mammals, platypuses are mammals, and they have mammary glands, but they don't have nipples, because their babies have beaks. And critters with beaks can't form a suction to suck a nipple and get milk out. And mammary glands, milk glands. Dude, they're modified sweat glands. So when you make mama milk, which my kids totally yumptialized for a long period of time, it was a long time, that is actually modified sweat. It's like sweat that my little milk ducks made that is full of, like, extra protein and extra fat, and it'll, like, give somebody fuel. Oh, my gosh, it's so crazy. Okay, are we finished? Are you finished? We'll do a quick overview and look at some of these critters to just kind of marvel at the diversity on the planet. But other than that, we're finished. Yes, you need to know this cladogram. Yes, you need to know the characters that define the points. If you think about it globally, if you think about it from an evolutionary perspective, I think it makes it easier. Like, what do they need? What is the characteristic that will give them an advantage that everybody beyond this shares? I don't think it'll be quite as overwhelming as perhaps it looks. I did put my whole cladogram on one piece of paper and I've tried to show it on here, and it doesn't show up very well. But I recommend it. And then maybe share it out with your classmates. That would be awesome, too. All right, let's do a quick overview of life on Earth.